Anti-aliasing not working in Normal bake
TexTools for Blender was recently released (free) which adds an anti-aliasing option for baking.



Internally the add-on just renders at 2x or 4x the size and then down-scales the final bake to the target resolution resulting in anti aliasing. The good thing is that this anti-aliasing works with all bake modes in TexTools.

You can find more information and download links from my website.